Bluetooth is a short-range radio link intended to replace cables connecting portable or fixed wireless enabled devices. Bluetooth links may be formed within the context of a piconet and the Bluetooth devices within the piconet may frequency hop together. One Bluetooth device may act as a master of the piconet, whereas the other devices may act as slaves. Under current Bluetooth specification, up to 8 active Bluetooth devices may participate in a single piconet. Active member addresses (AM_ADDR) 1 to 7 may be assigned to the active slaves during the creating of the piconet. The AM_ADDR may identify the destination slave of a master transmission or the source slave of a slave transmission. Using time division multiplexing, time may be divided into slots of 625 μs in a piconet, and transmissions may be synchronized to a slot grid and controlled by the master. The master and slaves Bluetooth devices may alternate transmit opportunities in a time-division duplex (TDD) fashion. Time may be divided into slots of 625 us in the piconet. In particular, the master may transmit on available even numbered slots, as defined by the master's Bluetooth clock, while the slave may transmit on available odd numbered slots. A slave may transmit only after being polled by the master. Bluetooth support both a point-to-point connection and a point-to-multipoint connection in which the channel may be shared among several Bluetooth slave devices. In the point-to-multipoint connection, the Bluetooth master may simultaneously transmit to its active slaves at one time. Different frequency hopping sequences may be used for each piconet in a Bluetooth network.
Bluetooth supports various types of links, both Synchronous Connection-Oriented (SCO) transport and Asynchronous Connection-Less (ACL) transport. A SCO link may be a symmetric point-to-point link between a master and a single slave in the piconet. The SCO link may be used to carry voice applications. Three SCO packets may be commonly used, namely, HV1, HV2, and HV3. The master may send SCO packets to a slave at regular intervals (TSCO) in reserved master-to-slave slots. The ACL link may be a point-to-multipoint link between the master and the slaves participating in the piconet and may be mainly used to carry data communications. In the slots not reserved for SCO transport, the master may establish an ACL transport on a per-slot basis to any slave. Among the various packet types defined by Bluetooth baseband, DH1, DH3, DH5, DM1, DM3 and DM5 may be commonly used for the ACL transport. An ACL packet may have a maximum duration of one, three and five time slots respectively.
The security features of the current Bluetooth specification provide secure communication at the link level. Depending on user requirements and sensitivity of information involved, Bluetooth security may comprise authentication, authorization, and encryption. The authentication may ensure that a device seeking a connection may be indeed who it claims to be. The authorization may determine whether or not a requesting device may be allowed access to specific information or services. The encryption may ensure confidentiality by protecting private data from being viewed/decoded by unintended recipients. A Bluetooth device may encrypt its transmissions and ensure that only a recipient with a proper decryption key may view/decode the data. Further, the Bluetooth specification may allow for a whole piconet's traffic to be encrypted. This may be achieved by encrypting traffic with a common encryption key shared by the devices within the piconet. In that case devices in the piconet may eavesdrop traffic of the Bluetooth network including traffic not intended for them.
Bluetooth has become a standard for personal area networks connecting mobile devices including mobile phones, PDAs, laptop computers, headsets, keyboards and other devices. Although Bluetooth may commonly be used to connect one device to another device, Bluetooth may, for example, be utilized for transmitting data from a master device to multiple slave devices through a Bluetooth broadcast service. When a master may be broadcasting to all slaves of the piconet, the slaves receiving broadcast baseband ACL packets do not transmit in odd numbered slots. Some fields in the received broadcast baseband ACL packets such as FLOW, ARQN and SEQN may not have significant meaning and may be wasted during the Bluetooth broadcast service. Current Bluetooth broadcast feature may repeat transmitting (broadcasting) the same broadcasted baseband ACL packet to the multiple slave devices several times to increase the reliability of broadcast over an unreliable Bluetooth radio channel.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.